We focus on the single-string ion trap approach and a single ion species, allowing one to encode qubits in an optical transition that can be operated with addressed laser light in the visible spectrum. For example, in \(^{40}{\rm Ca}^+\)  ions, the \(\left|0\right>\)  state corresponds to the ground state \(\left|S_{1/2},m_j=-1/2\right>\) , and the \(\left|1\right>\)  state to the metastable excited state \(\left|D_{5/2},m_j=-1/2\right>\) . We now briefly catalogue the set of physical gates we will utilise for these optical qubits in a static-string ion trap to implement QEC. References [1]}, [2]} provide a more detailed review of these gates.
